Model output discussion - winter proper underway

[blizzard81]

I share your frustration Tamara and cannot pick fault with anything you said in your post. I really do hope you continue to contribute on this forum as your analysis and expertise is second to none as far as I am concerned. 

[southbank]

43 minutes ago, johnholmes said:

An interesting comment that, re the output from Glosea, how do we know what it was suggesting as we have no sight of it?

In the fairly reliable time frame, and already commented on re the 500 mb anomaly charts. They, that I can get hold of, other than NOAA, both 6-10 and 8-14, have changed emphasis somewhat but in general a strongish westerly Atlantic flow from the bottom of the main Canadian trough into the UK then on into a relatively shallow European trough, on some, into the Mediterranean. So other than the 2-3 day colder spell post Xmas, and quite probably similar developing in the 2 week period behind deepish surface lows then no major cold outbreak seems likely.

beyond 2 weeks I leave to folk with a much greater understanding than I have.

If I may as an old 'un, make an observation on some of the posts re deep cold, what interests me is why, with UK Met models being constant in the 2-4 month outlooks re overall temperatures, upper air patterns, is why we got such a fairly deep cold outbreak this month. Nor have I any idea why UK Met, went fairly consistently for the colder option in their 6-30 day outlooks, in spite of what their 2-4 month input must have shown. Quite intriguing but I no longer have any contacts in the senior man's area so I will probably never know!

usual links below along with the ECMWF 500 mb anomaly charts via Meteo-c

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=101&map=0&type=0&archive=0

I think that is from the various tweets from IF (Ian Ferguson) who seems to stop posting here . Although at the time confidence was stated to be low there seemed to be a signal for SSW and more block weather , but these have definetly waned over the last week according to latest tweets.

[Chesil View]

Just now, johnholmes said:

An interesting comment that, re the output from Glosea, how do we know what it was suggesting as we have no sight of it?

In the fairly reliable time frame, and already commented on re the 500 mb anomaly charts. They, that I can get hold of, other than NOAA, both 6-10 and 8-14, have changed emphasis somewhat but in general a strongish westerly Atlantic flow from the bottom of the main Canadian trough into the UK then on into a relatively shallow European trough, on some, into the Mediterranean. So other than the 2-3 day colder spell post Xmas, and quite probably similar developing in the 2 week period behind deepish surface lows then no major cold outbreak seems likely.

beyond 2 weeks I leave to folk with a much greater understanding than I have.

If I may as an old 'un, make an observation on some of the posts re deep cold, what interests me is why, with UK Met models being constant in the 2-4 month outlooks re overall temperatures, upper air patterns, is why we got such a fairly deep cold outbreak this month. Nor have I any idea why UK Met, went fairly consistently for the colder option in their 6-30 day outlooks, in spite of what their 2-4 month input must have shown. Quite intriguing but I no longer have any contacts in the senior man's area so I will probably never know!

usual links below along with the ECMWF 500 mb anomaly charts via Meteo-c

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=101&map=0&type=0&archive=0

Regarding my comment that you find strange John .We know that because Fergie tweeted as such during the recent cold spell. If I recall the phrase he used in relation to Glosea went something along the lines of 'strongly suggestive of SSW' unless someone was misquoting him.

Edited December 21, 2017 by Broadmayne blizzard

[frosty ground]

The possibility of wintry weather after Christmas is still very much on, It looks to have firmed up a bit to.

[Chesil View]

I don't blame Tamara for giving up at all. If I was her I'd do the same. The teleconnections are what drives the Nwp. All Tamara has ever done is give her honest opinion of what they are suggesting at any given time along with what could scupper that outcome. The same as GP. This forum will be very very much the poorer without her.

[Timmytour]

30 minutes ago, karyo said:

Yes, the models perform quite well with mild mobile weather as it is the climatological norm for us. 

Actually it's worth bearing in mind how many times the GFS far reaches of FI stick us into winder wonderlands that never materialise. So it's not all about just reverting to the climatological norm.  There were certainly runs that picked up on the broad brush of the recent cold spell we had in advance of 10 days out, though of course without the consistency it's hard to give it credit on this.  The run in question that produced one of its first looks at Christmas Day was at a time where, as I recall,  nobody could see any reinvigoration of a lifeless Atlantic. Of course one run can never be taken in isolation.  But for me a relatively consistent approach by GFS to the further stretches of FI remains the best, though by no means infallible, of assuming what weather we will end up getting.  Beyond that, while i have seen plenty of theories that tickle my cold loving palate, nothing stands out to me yet as more valuable than the proverbial broken clock

[ACCOUNT DELETED]

GEFS 6z 192hrs for Porthcawl near Swansea, shows a trend of turning colder from Christmas Day to slightly below average. Any heavy showers could contain hail & thunder on the coasts but there should be more sunshine around compared to what we're getting at the moment....... zilch! 

Edited December 21, 2017 by Draig Goch

[TEITS]

Sadly the 06Z indicates exactly what I was referring to earlier.

[stewfox]

1 hour ago, TEITS said:

Only positive for the New year is the ouput can only get better because it cannot get any worse.

 

I know its T240 but New Years Eve 6am 12/13c . Cant get any worse surely ??

 

 

 

[karyo]

1 minute ago, stewfox said:

 

I know its T240 but New Years Eve 6am 12/13c . Cant get any worse surely ??

 

 

 

At least it will be mild for those of us who will be partying that weekend. No need to get a coat and pay for the cloakroom.

[Britneyfan]

Ooo would love new year to reach 16 degrees fingers crossed 

[cheshire snow]

12 minutes ago, stewfox said:

 

I know its T240 but New Years Eve 6am 12/13c . Cant get any worse surely ??

 

 

 

Not out of the Question by any means Left for work at 0545 this morning and the Temperature was 9.7c

C.S

[mulzy]

43 minutes ago, TEITS said:

Sadly the 06Z indicates exactly what I was referring to earlier.

The shift to move the jet SW to NE often happens after a period of very unsettled weather - seen it so many times over the years. Maybe this is what the MO were alluding to in their long ranger?  Anyway, time will tell as ever!

[Weather-history]

31 minutes ago, stewfox said:

 

I know its T240 but New Years Eve 6am 12/13c . Cant get any worse surely ??

 

 

 

 

The severe winter of 1916-17 had one of the mildest New Year's Days in the record books

[lassie23]

Looks like we will get a southerly feed for early January with possible mid teen temps in the south, but then will that high start heading north and bring that expected easterly, which I still think will happen, or am I just bonkers

[Daniel*]

That’s a great shame Tamara. I find it quite disturbing how an individual who has done extensive reading, starting from nothing, has such a wealth of knowledge. And is ridiculed you can’t argue with the science, Tamara, always highlights the caveats - no wonder she doesn’t forecast what makes it all more baffling. This one-upmanship needs to stop at once, and TEITS I’ve seen very little signal of very mild SW’ly so a bit of a cherrypick 10 days out..

I’ve read it’s a bad as it gets? Hyperbole quite frankly a 3-4 day cold snap/spell is now firmly agreed upon and with that the chance of snow even possible away from usual places. 

[frosty ground]

Again people are taking the OP at face value at a range of 10 days.....



As you can see the Op is one of the mildest runs for that day and not really supported. Range of options still on the table.

[Glacier Point]

Today's (GFS) tropical outlook underscores why we are heading for a substantive drop in angular momentum.

The only bit of forcing being 60W, lots of easterly wind addition across the Tropical Pacific and northward momentum transport.

To rub this in, GFS also predicting a -ve zonal winds developing in the upper stratosphere over the Equator, which will add easterly inertia to overall angular momentum budgets.

Net result is that were are heading for GWO phase 2 New Year onwards. As a basic template, low to the west, ridge to the east but not far enough west or north to bring about an easterly flow and not conducive for cold outbreaks to our east.

[bluearmy]

@tamara - you shouldn’t be surprised that much of your posts are not read properly. I think the problem you had over the past few weeks was that it was ‘cold on the ground with snow’ and some posters here and the met Office were seeing cold ahead in their models etc for jan. You wanted to remain on the fence but I felt that developments in the Pacific pushed you into landing on the ‘cold side’ going forward.  Whether that’s the right or wrong decision remains unknown but some are bound to sadly react badly to ‘apparently ‘having their snow taken away’ from them ! 

[mulzy]

16 minutes ago, Daniel* said:

That’s a great shame Tamara. I find it quite disturbing how an individual who has done extensive reading, starting from nothing, has such a wealth of knowledge. And is ridiculed you can’t argue with the science, Tamara, always highlights the caveats - no wonder she doesn’t forecast what makes it all more baffling. This one-upmanship needs to stop at once, and TEITS I’ve seen very little signal of very mild SW’ly so a bit of a cherrypick 10 days out..

I’ve read it’s a bad as it gets? Hyperbole quite frankly a 3-4 day cold snap/spell is now firmly agreed upon and with that the chance of snow even possible away from usual places. 

As it stands, I would take the GEFS with a pinch of salt - the EPS nowhere near as cold.  A shift from well above normal temperatures to normal, maybe just below normal (for the south) with the continuing possibility of snow over high ground in the north seems the best call at the moment.

http://www.meteo24.fr/fr/home/meteo-france-et-europe/passion-meteo/ensemble-de-previsions.html?eps=london

 

 

Edited December 21, 2017 by mulzy

[Derecho]

Afternoon

Some quite varied interpretations of the model output so I thought I’d summarise my interpretation of the output in the simplest way I can to aid new members.

A few days ago I mentioned the possibility of a split in the polar vortex from the high pressure cell over NW Canada. Indeed that now looks to be happening with this synoptic picture at T96. The PV is split like a knife through hot butter.



Now this is no guarantee of a sustained cold spell over our part of the world, indeed it depends on whether the blocking can sustain itself and where the lobes of the polar vortex fall.

Here is the synoptic picture another 2 days later, unfortunately two things go wrong:



-  Although pressure is encouraged to build over Greenland, the mild air doesn’t reach this area. It is a cold based high and therefore pressure only really builds over Greenland.

-  The cold shot of air heading into Canada moves ESE instead of S due to the high pressure sinking to the south-east USA.

As a result, the lobe of the polar vortex over Russia moves into the arctic and the Atlantic fires up due to the cold air leaving NE Canada. The result is that the vortex is fusing back together and our chance to build some good northern blocking in our part of the world is gone.

Where does this leave our longer term prospects?

Well the Atlantic will probably be quite active due to all that cold air over the NE of Canada spilling out into the ocean, so it may be a little while till we get another blocked pattern.

I wouldn’t get too despondent though unless we start seeing height rises to our south and south east. A possibility but quite a few ensemble members don’t build heights there. With that in mind we may get transient northerlies or ridges of high pressure coming in. Something may pop up at short notice.

 

So fingers crossed we don’t get the height rises to our immediate S/SE, no white flag waving from me yet. December 2015 this is not, it ain't ideal but that’s the British climate for you!

Edited December 21, 2017 by Quicksilver1989

[northwestsnow]

Well further to my post about EC snow depth charts Exeter suggesting cold air moving south Boxing day with rain turning to snow in the north and basically unsettled but cold enough for hill snow in the north.

The only question is what defines 'hills' - locally the hills extend to 300m+, so with that in mind (and after viewing GFS6z) i think its only right and fair to suggest some places could well get a dumping next week.

Could be the heights ridging to our north are just about doing enough to see the jet dig far enough south to allow for PM attacks to engulf Northern Britain..

[bluearmy]

4 minutes ago, Glacier Point said:

Today's (GFS) tropical outlook underscores why we are heading for a substantive drop in angular momentum.

The only bit of forcing being 60W, lots of easterly wind addition across the Tropical Pacific and northward momentum transport.

To rub this in, GFS also predicting a -ve zonal winds developing in the upper stratosphere over the Equator, which will add easterly inertia to overall angular momentum budgets.

Net result is that were are heading for GWO phase 2 New Year onwards. As a basic template, low to the west, ridge to the east but not far enough west or north to bring about an easterly flow and not conducive for cold outbreaks to our east.

I know a few in here didn’t see that composite as being as poor as it apparently is yesterday.  Things rarely end up looking exactly like the composites and analogues - I would rather take that composite starting point as a base and see whether we shift that a bit n/s/e/w over the period. 

Also, the ec46 might be a bit more interesting weeks 3 and 4 as the clusters this morning show one nw European troughy one and the others are all headed to a less low anomoly area with varied high anomolys showing 

[Frosty.]

It looks like a generally unsettled spell is on the way which is expected to last well into early January but I don't see constant mild, I think temperatures fluctuating around average is a good way of describing the upcoming more disturbed pattern with some potentially large swings between milder and colder air..following the utter numbing tedium of this week, I will take that!

Edited December 21, 2017 by Frosty.

[N/A]

@Draig Goch

Just had a look through a lot of models and I don't see any real concerns regarding stormy lows near us next week just our usual wind & rain with mild air followed by colder air followed by milder air and so on. It will as you said in your last post be cold enough for hail (some recent years we didn't even see that as it was too mild) with some temporary accumulations in the heavy showers and perhaps more thunder & lightning to come again triggered from the still relatively mild sea.

As I've said all along February is often referred to our 'snowy month' when the sea temperatures are at their coldest and although the sun is gaining strength it is still fairly weak. Personally I haven't been looking too much at snow probabilities in my area and won't start until around the 3rd week of January unless anything significant shows up within a timeframe of 4 days maximum on the charts. Until then we have far more chance of the ground turning white through hailstones rather than snow.